Temperature responsive element



Dec. 7, 1943. A, QQGROQMS 2,336,092

TEMPERAIQBE RESPONSIVE ELEMENT Filed Dec. 29, 1941 Fatented Dec; 7, 1943I TEMPERATURE RESPONSIVE ELELIENT Albert 0. Grooms, Dayton, Ohio,assignor to General Motors Corporation, Dayton, Ohio, a corporation ofDelaware Application December 29, 1941, Serial No. 424,727

3 Claims.

ous attempts have been made to wrap the capillary tube at its end toapproximate a bulb. Such forms involve a wrapping problem and, where awell is used, they do not provide very good contact with the well.

It is an object of my invention to provide an end upon a capillary tubewhich will fit into a well and provide good thermal contact with thewell.

It is another object of my invention to provide an end upon a capillarytube which will press firmly against the interior walls of the well overa considerable length of tubing to provide good thermal contact.

It is another object of my invention to provide an end of a capillarytube which will use the inherent spring or elasticity of the tubing topress sections of the tubing tightly against the interior walls of awell.

These objects are attained by providing a closed loop upon the end ofthe capillary tube which is slightly larger than the well so that thewell will receive the looped end in a compressed condition.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing, wherein a preferred form of the present invention is clearlyshown.

In the drawing:

Fig. 1 is a diagrammatic view of a refrigerating system embodying oneform of my invention;

Fig. 2 is an enlarged sectional view of the looped end of the capillarytubing in the well as shown in Fig. 1; and

Fig. 3 is a view of the looped end as it is withdrawn from the well.

Referring now to the drawing, there is shown a refrigerating systemincluding a compressor 20 driven by an electric motor 22 for compressingthe refrigerant and for forwarding the compressed refrigerant to acondenser 24 where it is liquefied. The liquefied refrigerant iscollected in a receiver 26 and conducted, under the control of asuitable expansion valve 28, to an evap- ..orating means 30, shownbonded to the walls of a container 32 to be kept cool. The refrigerantevaporates within the evaporator 30 under reduced pressure and isreturned to the compressor 20. The container 32 is provided with a well36 in intimate contact therewith. The operation of the system iscontrolled by a snap-acting switch means 38 connected in series with oneof the conductors of the electric motor 22. Thisswitch 38 is operated bya bellows 40, to which is connected a capillary tube 42 of suflicientlength to reach the interior of the well 36.

This capillary tube 42 and the bellows 40 are preferably charged with avolatile liquid or vapor so that the pressure within the tube andbellows will correspond to the temperature at the colde est point in thetubing. Thecoldest point of the tubing is naturally in the portion inthe well 36. It is desirable that the capillary tubing within the wellrespond as closely as possible to the temperature of the container 32.This requires very good thermal contact between the well 36 and thecapillary tube 42.

In order to secure this good thermal contact,

I reverse the end of the capillary tube 42 upon itself to provide areversed section 44 which is formed substantially into the shape of anellipse and soldered to the other portion of the tubing 34, asdesignated by the reference character 46. This forms the end of the tubeinto a full elliptic spring since the capillary tubing naturally has acertain amount of spring or resiliency common to all metal tubing. Thisspring or resiliency naturally depends upon the characteristics of themetal used, and it is therefore desirable, in order to carry out thisinvention, that the capillary tubing be formed of some suitable metalwhich provides suflicient resiliency.

As shown in Fig. 3, the loop should have its sides so formed that theyextend in a bowed fashion when not compressed so that they may be spreadsomewhat wider than the interior of the well 36. When shaped in thismanner. the tube is compressed when inserted into the well, as shown inFig. 2, and the sides of the loop are pressed tightly against theinterior walls of the well for a considerable length due to the springaction of the elliptical shape of the loop. In this way, very goodthermal contact is obtained between the looped end of the capillary tube42 and the well 36 so that the control ofthe system by the switch 38very closely conforms to the temperature of the container 32 in orderthat the container may be kept at the desired temperature by therefrigeration system. The well may be sealed by a suitable stopper 50.

While the form of embodiment of the invention as herein disclosed.constitutes a preferred form, it is to be understood that other formsmight be a claims which follow.

What is claimed is as follows: 1. A temperature responsive elementincludhaving at least a limited amount of resiliency, a section of thetube being reversed upon itself, and the free end portion of thereversed section of the tube being fastened to the other section to forma complete resilient looped section generally in the form ofan elipsecapable of acting to a limited degree as a full elliptic spring, saidtube forming the complete looped section as well as the sole fluidconnection between the looped section and the motor.

2. A temperature responsive element including a fluid motor and a fluidcontaining tube having at least alimited amount of resiliency, a sectionof the tube being reversed upon itself, the free end portion of thereversed section oi the tube being fastened to the other section to forma complete resilient looped section generally in the form of an elipsecapable of acting to a limited degree as a full elliptic spring, and adopted, all coming within the scope of the V ing a fluid motor and afluid containing tube well smaller transversely than the looped sectionreceiving said looped section in a compressed condition so that theinherent resiliency of the looped section causes the opposite sides ofthe loop to be pressed against the interior sides of the well to insuregood thermal contact, said tube forming the complete looped section aswell as the sole fluid connection between the looped section and themotor. 7

3. A temperature responsive element including a fluid motor and a fluidcontaining tube of substantially capillary size having at least alimited amount of resiliency, a section of the tube being reversed uponitself by a normal bend in the tube,

and a well smaller than the reversed section receiving said reversedsection in a compressed condition so that the inherent resiliency of thereversed section causes the opposite sides of the reversed section andthe adjacent section to be pressed tightly against the interior walls ofthe well to insure good thermal contact, said tube forming the completelooped section as well as the sole fluid connection between the loopedsection and the motor.

ALBERT O. GROOMS.

